Plasma etching method using heptafluoropropyl methyl ether and heptafluoroisopropyl methyl ether

Abstract

Disclosed is a plasma etching method. The plasma etching method may comprise: a first step for vaporizing liquid heptafluoropropyl methyl ether (HFE-347mcc3) and liquid heptafluoroisopropyl methyl ether (HFE-347mmy); a second step for supplying a mixed gas containing the vaporized heptafluoropropyl methyl ether and the heptafluoroisopropyl methyl ether and a discharge gas containing argon gas to a plasma chamber in which an etching target is arranged; and a third step for discharging the discharge gas to generate plasma, and using the plasma to plasma etch the etching target.

1 . A plasma etching method comprising:
 a first step of vaporizing each of liquid heptafluoropropyl methyl ether (HFE-347mcc3) and liquid heptafluoroisopropyl methyl ether (HFE-347mmy);   a second step of supplying a discharge gas including a mixed gas and argon gas to a plasma chamber in which an etching target is received, wherein the mixed gas includes the vaporized heptafluoropropyl methyl ether and the vaporized heptafluoroisopropyl methyl ether and; and   a third step of discharging the discharge gas to generate plasma, and plasma-etching the etching target using the generated plasma.   
     
     
         2 . The plasma etching method of  claim 1 , wherein in order to vaporize the liquid heptafluoropropyl methyl ether and provide the vaporized heptafluoropropyl methyl ether to the plasma chamber, a first container receiving therein the liquid heptafluoropropyl methyl ether is heated to a first temperature equal to or higher than a boiling point of the heptafluoropropyl methyl ether, and a connection pipe connecting the first container and the plasma chamber to each other is heated to a second temperature higher than the first temperature. 
     
     
         3 . The plasma etching method of  claim 1 , wherein in order to vaporize the liquid heptafluoroisopropyl methyl ether and provide the vaporized heptafluoroisopropyl methyl ether to the plasma chamber, a second container receiving therein the liquid heptafluoroisopropyl methyl ether is heated to a third temperature equal to or higher than a boiling point of the heptafluoroisopropyl methyl ether, and a connection pipe connecting the second container and the plasma chamber to each other is heated to a fourth temperature higher than the third temperature. 
     
     
         4 . The plasma etching method of  claim 1 , wherein the mixed gas and the argon gas are supplied to the plasma chamber at a flow rate ratio of 1:2,
 wherein the vaporized heptafluoropropyl methyl ether and the vaporized heptafluoroisopropyl methyl ether in the mixed gas are supplied to the plasma chamber at a flow rate ratio of 1:3 to 3:1.   
     
     
         5 . The plasma etching method of  claim 1 , wherein a bias voltage of −800 to −1200V is applied to a substrate supporting the etching target in the plasma chamber during the third step. 
     
     
         6 . The plasma etching method of  claim 1 , wherein the etching target is a semiconductor substrate on which an amorphous carbon layer (ACL) is formed on a silicon substrate and a silicon oxide thin film or a silicon nitride thin film is formed thereon. 
     
     
         7 . The plasma etching method of  claim 6 , wherein the mixed gas and the argon gas are supplied to the plasma chamber at a flow rate ratio of 1:2,
 wherein the vaporized heptafluoropropyl methyl ether and the vaporized heptafluoroisopropyl methyl ether in the mixed gas are supplied to the plasma chamber at a flow rate ratio in a range of 1:2.3 to 2.3:1.   
     
     
         8 . The plasma etching method of  claim 7 , wherein after the third step, a ratio of an etch selectivity of the silicon oxide thin film or the silicon nitride thin film with respect to an etch selectivity of the silicon substrate is 7.5 or greater. 
     
     
         9 . The plasma etching method of  claim 7 , wherein after the third step, a ratio of an etch selectivity of the silicon oxide thin film or the silicon nitride thin film with respect to an etch selectivity of the amorphous carbon layer (ACL) is 10 or greater. 
     
     
         10 . The plasma etching method of  claim 8 , wherein a bias voltage of −800 to −1200V is applied to a substrate supporting the etching target in the plasma chamber during the third step,
 wherein as a magnitude of the applied bias voltage increases, the ratio of the etch selectivity of the silicon oxide thin film or the silicon nitride thin film with respect to the etch selectivity of each of the silicon substrate and the amorphous carbon layer (ACL) decreases.